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<br /> Phase II Contaminant Delineation Investigation
<br /> Central California Traction Company
<br /> ' 1645 Cherokee Lane,Stockton,CA
<br /> Hydro-Environniental Technologies, Inc
<br /> 10 SITE LOCATION AND BACKGROUND
<br /> ' The subject property is at 1645 Cherokee Lane, Stockton, California, north of the intersection of
<br /> Cherokee Lane and Waterloo Road The subject property is in an area of Axed light-industrial and
<br /> commercial buildings, it is part of a property used by the Central California Traction Company to repair
<br /> railroad engines In January 1999, Thorpe Oil Company excavated and removed one 6,000-gallon
<br /> gasoline undeiground storage tank (UST) and one 1,000-gallon diesel UST from the subject property
<br /> ' One soil sample, collected from below the excavated diesel tank at 9 feet below surface grade (bsg), had
<br /> 5,000 milligrams per kilogram (mg/kg) total petroleum hydrocarbons (TPH) as diesel, 0 33 mglkg
<br /> toluene, 0 740 mg/kg ethylbenzene, and 1,800 mg/kg total xylenes, benzene was below method detection
<br /> liriiits
<br /> HETI reviewed the September 1999 URS Greiner Woodward Clyde (URSGWC) final report UST
<br /> Investigation, 1645 Cherokee Lane, Stockton, CA In August 1999, URSGWC conducted a soil
<br /> boring/ground water investigation Five borings were drilled using direct push (DP) and hollow stem
<br /> auger The highest TPH. as diesel concentrations (at 22,000 mg/kg) in soil were detected in samples
<br /> collected from boring B-1 at the 10-foot depth interval However, TPH as diesel was detected in soil
<br /> samples collected from the entire soil boring to giound water Concentrations ranged from 6,000 mg/kg
<br /> (at 15-feet bsg) to 2,000 mg/kg (at 40-feet bsg) Ethylbenzene and total xylenes were also detected
<br /> ranging to 0 011 mg/kg and 0 061 mg/kg, respectively, at 10 teet bsg
<br /> In their November 4, 1999 letter, the San Joaquin County PHS/EHD requested a further investigation to
<br /> determine the lateral and vertical extent of the petroleum contamination at the subject property HETI
<br /> ' installed six DP borings throughout the subject pioperty Grab ground water samples were obtained from
<br /> each boring No detectable concentiations of TPH as gasoline, TPH as diesel, benzene, toluene,
<br /> ethylbenzene and total xylenes (BTEX), or the five fuel oxygenates were found in the 46 soil samples and
<br /> six grab ground water samples submitted for analysis HETI then installed three monitoring wells (MW-1
<br /> - MW-3) to determine the depth to ground watei and to sample giound water TPH as diesel was detected
<br /> in all three ground water monitoring wells (Table 2) No detectable concentrations of TPH as gasoline,
<br /> BTEX, the five fuel oxygenates, 1,2-dichloroethane (1,2-DCA), or 1,2-dibromoethane (EDB) were found
<br /> in the ground water samples submitted for analysis From gauging data obtained in 2000 and 2001, HETI
<br /> infers the direction of ground water flow across the site a5 ranging from northeastward to northwestward,
<br /> possibly influenced by the periodic pumping of local irrigation wells
<br /> ' In September 2000, HETI began quarterly ground water monitoring at the subject site During the first
<br /> quarter of ground water monitoring, TPH as diesel was detected in MW-1 and MW-3 No detectable
<br /> 1 concentration of TPH as diesel was found in MW-2 No detectable concentrations of TPH as gasoline,
<br /> BTEX, the five fuel oxygenates, 1,2-DCA, or EDB were found in the ground water samples submitted for
<br /> analysis During the August 2001 sampling round, MW-2 and MW-3 were dry and no samples were
<br /> ' collected A sample was collected from MW-1, however, the laboratory's quality control failed to
<br /> produce results within acceptable detection ranges Also in August 2001, one additional ground water
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